The objective of the proposed research and development is to identify protein antigens specific for Cryptosporidium parvum and microsporidia species that will enable the development of a simple, rapid immunoasssy device for the detection of these organisms in stool samples. The device will also contain tests for the detection of giardia lamblia and Entamoeba histolytica. The availability of this product will substantially reduce that need or complex, labor-intensive ova and parasite examinations and will provide a faster test result for timely patient care. In phase I of this proposal, the most highly expressed protein antigens specific for C. Parvum and microsporidia species will be identified. These protein antigens will be used to produce antibodies that can be used to select the most abundant protein antigens that are expressed in a cDNA library that produces protein antigens representing all stages parasites life cycle.